A task force of the International Association for the Study of Pain (IASP) proposes a classification of chronic pain as either chronic primary or chronic secondary pain, when chronic pain represents the major complaint (ie, in chronic pain syndromes) and when chronic pain is secondary to a chronic disorder (eg, chronic neuropathic pain), respectively. This classification is included in the International Classification of Diseases, 11th revision (ICD-11) and was published in Pain.

Panel experts formulated definitions and characteristics for pain diagnoses that included precisions on the severity, time course, and presence of psychologic or social determinants of pain. Prior to publication, these updates were presented at the 2016 World Congress on Pain and at the 2017 European Pain Congress annual meetings, during which conference attendees were invited to provide comment on these classifications through the World Health Organization proposal platform as well as through the IASP website. The early version of the classification was pilot-tested in 4 countries.

Chronic pain was defined as “pain that persists past normal healing time and hence lacks the acute warning function of physiological nociception.” The following 8 syndromes were classified:

  • Chronic primary pain syndromes were defined as pain in ≥1 anatomic region that is either persistent or recurs for >3 months and causes functional disability or emotional distress. Chronic primary pain syndromes were also defined as pain that cannot be accounted for by any other chronic pain disorder.
  • In chronic secondary pain syndromes, a disease is the underlying cause for chronic pain, which is considered a symptom of that disease.
  • Chronic cancer-related pain encompasses pain that is caused by a primary tumor, metastases, or cancer treatment, including chemotherapy, surgery, and radiotherapy.
  • Chronic postsurgical or posttraumatic pain includes pain that arises following surgery or trauma and that is often neuropathic in nature.
  • Chronic neuropathic pain represents pain that is a result of a disease or lesion of the somatosensory nervous system.
  • Chronic headache or orofacial pain is defined as headache of orofacial pain that occurs for >2 hours per day on ≥50% of days for ≥3 months.
  • Chronic secondary visceral pain refers to recurrent or persistent pain that stems from internal organs of the neck and/or head as well as cavities of the thorax, abdomen, and pelvis.
  • Chronic secondary musculoskeletal pain is defined by recurrent or persistent pain that occurs in association with a disease affecting the bones, muscles, joints, or related soft tissue(s).

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“This simple to use classification is also expected to improve access to multimodal care for all patients with chronic pain,” noted the authors. “It will facilitate accurate epidemiological investigations and health policy decisions regarding chronic pain, including adequate financing of treatments.”

Reference

Treede RD, Rief W, Barke A, et al. Chronic pain as a symptom or a disease: the IASP Classification of Chronic Pain for the International Classification of Diseases (ICD-11). Pain. 2019;160(1):19-27.

This article originally appeared on Clinical Pain Advisor